/*
 * Created on 13 May 2008
 * Created by Allan Crooks
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package com.aelitis.azureus.core.util;

import java.util.HashMap;
import java.util.Map;

/**
 * @author Allan Crooks
 * 
 */
public class CopyOnWriteMap<K, V> {
    private volatile Map<K, V> map;

    public CopyOnWriteMap() {
        this.map = new HashMap<K, V>(4);
    }

    public V put(K key, V val) {
        synchronized (this) {
            HashMap<K, V> new_map = new HashMap<K, V>(map);
            V result = new_map.put(key, val);
            this.map = new_map;
            return (result);
        }
    }

    public void putAll(Map<K, V> m) {
        synchronized (this) {
            HashMap<K, V> new_map = new HashMap<K, V>(map);
            new_map.putAll(m);
            this.map = new_map;
        }
    }

    public void putAll(CopyOnWriteMap<K, V> m) {
        putAll(m.map);
    }

    public V remove(Object key) {
        synchronized (this) {
            HashMap<K, V> new_map = new HashMap<K, V>(map);
            V res = new_map.remove(key);
            this.map = new_map;
            return res;
        }
    }

    public V get(K key) {
        return this.map.get(key);
    }

    public int size() {
        return this.map.size();
    }

    public boolean isEmpty() {
        return this.map.isEmpty();
    }

    /*
     * shouldn't return underlying map directly as open to abuse. either wrap in unmodifyable map or implement desired features explicitly public Map
     * getMap() { return this.map; }
     */
}
